Timing HTTP Requests with cURL

Sometimes you just need to quickly benchmark how fast a page can be loaded (or fetched to be more precise). For these cases, cURL is a great option for timing HTTP requests.

$ curl -s -w "%{time_total}\n" -o /dev/null http://www.google.com/

Want a few more datapoints?? Thanks to ZSH, it’s easy to just loop around it:

$ for i in {1..3}; curl -s -w "%{time_total}\n" -o /dev/null http://www.google.com/

And if you’re a bash lover:

$ for i in {1..3};do curl -s -w "%{time_total}\n" -o /dev/null http://www.google.com/; done

Default behavior on cURL is GET, but you can do POST, DELETE, PUT and more complex requests. If you’re not familiar with cURL, best place to start is the manpage.

Besides “time_total”, curl also provides other timing, like “time_namelookup”, “time_connect”, etc. Checking a post by Joseph, I remembered that curl supports formatted output. This way we can create a “template” for our HTTP timing test:

Assuming the format file is named “curl-format”, we can execute a request:

$ curl -w "@curl-format" -o /dev/null -s http://www.google.com/
            time_namelookup:  0.416
               time_connect:  0.435
            time_appconnect:  0.000
           time_pretransfer:  0.435
              time_redirect:  0.000
         time_starttransfer:  0.488
                 time_total:  0.491


  • -w “@curl-format” tells cURL to use our format file
  • -o /dev/null redirects the output of the request to /dev/null
  • -s tells cURL not to show a progress bar
  • http://www.google.com/ is the URL we are requesting

The timings are DNS lookup, TCP connect, pre-transfer negotiations, start to end of transfer, redirects (in this case there were none), time to first byte, and total time (last byte), respectively.

Looking for something a bit more “complete”? You can always try Apache Benchmark:

$ ab -n 3 http://www.google.com/
This is ApacheBench, Version 2.3 <$Revision: 655654 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/
Benchmarking www.google.com (be patient).....done
Server Software: gws
Server Hostname: www.google.com
Server Port: 80
Document Path: /
Document Length: 10928 bytes
Concurrency Level: 1
Time taken for tests: 0.231 seconds
Complete requests: 3
Failed requests: 2
(Connect: 0, Receive: 0, Length: 2, Exceptions: 0)
Write errors: 0
Total transferred: 35279 bytes
HTML transferred: 32984 bytes
Requests per second: 12.99 [#/sec] (mean)
Time per request: 76.999 [ms] (mean)
Time per request: 76.999 [ms] (mean, across all concurrent requests)
Transfer rate: 149.15 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 19 21 1.8 22 22
Processing: 50 56 5.3 59 61
Waiting: 46 51 4.0 53 53
Total: 73 77 5.0 79 82
Percentage of the requests served within a certain time (ms)
50% 76
66% 76
75% 82
80% 82
90% 82
95% 82
98% 82
99% 82
100% 82 (longest request)


A lot of corporations have seen dramatic decreases in revenue and have cut back projects as well. In many cases, this is accompanied by layoffs, and so everyone is working far harder.

But in other organizations, and for a lot of freelancers, there’s more time than work. In other words, slack time.

Assume for a moment you don’t have money to develop and launch something new. So, what are you going to do with the slack?

What can you build over the next year that will take time now and pay off later? How can you invest the slack to build a marketing asset that you’ll own forever?

May I offer two suggestions:

1. Learn something. Become an expert. For free, using nothing but time, you can become a master of CSS or HTML or learn Python. You can hit the library and read the entire works of important authors, or you can borrow some books from a friend and master Analytics or discover case studies and corporate histories that will be invaluable in a year. You could learn to become fluent in Spanish…

If you’re a glass blower without a job, you can’t do much glass blowing. But if you’re a digital marketer between gigs, you can do a lot of digital marketing… build a tribe for your favorite non-profit and make it a case-study for an entire industry.

2. Earn a following and reputation. Use social networking tools to connect to people for no good reason. Post tons of useful answers on discussion boards where your expertise is valued. Build a permission asset in the form of an email newsletter or a fascinating blog that people want to read. Do resume makeovers for 100 friends. Start a neighborhood or industry book group. Don’t go to conventions, earn the right to speak at them.

If you were as serious about these two endeavors as you are about doing your job (eight hours a day on a slow day), imagine how much more powerful and in demand you’ll be a year from now.

Beats the alternative, by far.